Determinants of Sweetpotato Commercialization in South
Nyanza, Kenya
By Jan W. Low
International Potato Center
Nairobi, Kenya
Paper Presented at the Sixth Triennial Symposium of the International Society
for Tropical Root Crops---Africa Branch
Capital City, Lilongwe, Malawi
22-28 October 1995
Abstract
Sweetpotato serves as an important food security crop in many parts of Kenya, but rarely is a
principal food staple or significant cash crop. A structured household survey conducted
among 81 sweetpotato growers examines the factors influencing the extent to which farmers
engage in commercial sweetpotato production in four distinct agro-ecologies in South
Nyanza, the major sweetpotato growing area in Kenya. The sample is purposively stratified
on agro-ecological conditions, road access, age of the sweetpotato grower, and gender of
the household head. Marketing constraints emerge as the most limiting factor to expanding
sweetpotato production and insufficient planting material and weevil infestation are also
important constraints in drier agro-ecologies. Men typically cultivate sweetpotato only when
the crop becomes commercially important. Differences in varietal characteristics preferred
by commercial and non-commercial producers of sweetpotato are explored.
Introduction
Nyanza Province, consisting of the districts surrounding Lake Victoria to the east and to the north, is
Kenya’s principal sweetpotato growing area. According to the Ministry of Agriculture, in 1990-91 some 52% of all
sweetpotatoes grown in the country hailed from South Nyanza district (Kenya Ministry of Agriculture, 1992). The
district has since been split into four entities (Homa Bay, Migori, Kuria, and Suba) with Homa Bay District being
the principal source of sweetpotatoes. Since most secondary data (e.g. National Census in 1989) are based on
the previous boundaries, the South Nyanza terminology will be retained in this paper.
Previous work conducted by Mutuura, et. al. (1992) established that sweetpotato is an important food
security crop in many parts of Kenya, particularly when maize yields are low and in months when other foods are
scarce. Smit and Matengo (1995) documented farmers’ cultural practices for sweetpotato in South Nyanza,
noting the growing importance of sweetpotato as a cash crop in certain areas of the district.
This study builds upon this previous work by seeking to understand the determinants of commercialization in
South Nyanza, emphasizing differing agro-climatic conditions, infrastructure, life-cycle, and gender
considerations which may affect an individual’s decision to sell sweetpotatoes. Specific objectives include:
(1) Describe the constraints faced by farmers located in distinct agro-ecological settings
regarding sweetpotato production and marketing.
(2) Identify viable indicator variables which can be successfully used to distinguish
commercialized versus non-commercialized sweetpotato growing households.
(3) Ascertain the most significant determinants of commercialized sweetpotato production.
(4) Investigate whether farmers selling sweetpotatoes have preferences in varietal
characteristics that are distinctly different from farmers cultivating sweetpotato for home
consumption only.
Methodology
1
Study Areas. Four distinct areas were chosen in South Nyanza, three from Homa Bay District and one from
Migori District (Rongo), each being distinct in annual rainfall patterns (Fig. 1), soil type, and the relative
importance of sweetpotato to the household.
(1) In Rongo division, annual rainfall averages 1600, with monthly mean precipitation falling below 100 mm
only in the month of July. Most of the location falls in the lower midland sugarcane zone (LM1) (Jaetzold and
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Schmidt, 1982), with altitudes ranging from 1300 to 1500 m and annual mean temperatures of 21.7 -20.5 C.
Sweetpotato is planted two times a year, May-early July during the long rains, and November through Mid-
December during the short rains (Fig. 1). Soils are predominantly humic acrisols of low fertility, with the majority
of farmers surveyed (81%) planting sweetpotatoes on sandy loams (kuoyo in Luo, the local language).
1
Kenya’s administrative categories are as follows: Province, District, Division, Location, Sub-Location, Village.
(2) Kabondo division is widely recognized for its commercial sweetpotato production. Located in the upper
midland zones (UM1-3) with agro-climatic conditions favorable for coffee and maize production (Jaetzold and
Schmidt, 1982), sweetpotato has emerged as a much more important cash crop than coffee in the area during
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the past 10 years. Altitudes range from 1450-1700 m, with annual mean temperatures from 21.1 -19.3 C and
annual precipitation levels similar to that of Rongo’s (1598 mm). Sweetpotato is planted three times a year, Mid-
March through June, July through August (the middle rains), and in October through November. Over 70% of
growers reported June plantings, primarily aimed at harvesting during Ramadan, an important Muslim holiday for
which sweetpotato is typically in high demand (Fig. 1). Soils are classified as chromo-luvic phaeozems of
moderate to high fertility, with 70% of farmers planting their sweetpotato on clay loams (lwala).
(3) The Ndhiwa area consists of two divisions, Ndhiwa and Nyarongi, which used to be both part of the same
division. The area is noted for its heavy, difficult to manage black cotton soils (anywang’), which occasionally are
mixed with sandy loams or clay loams. These two main soil types, pure vertisols (black cotton) and verto-luvic
phaeozems, are considered to be of moderate and high fertility, respectively. Most of the division falls either
under the cotton (LM3) or the lower midland marginal sugar cane zone (LM2), with conditions for growing maize
ranging from fair to good (Jaetzold and Schmidt, 1982). However, no cotton was being grown in the area
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surveyed. Altitudes range from 1300-1500 m and average annual temperatures are 21.7 -20.5 C. Annual
rainfall averages 1372 mm, with sweetpotato planting concentrated in the months of April through June, and in
October through November. The past isolation of the area is being alleviated by the recent completion
(September 1995) of a tarmac road through the center of the area.
(4) The Kendu Bay area for the study includes households from the East Karachuonyo division (previously part
of the former Kendu Bay division). This dry agro-ecology typically only has one sweetpotato planting season for
households without access to swamp land: from March through Mid-June during the main rains. Annual rainfall
averages 1134 mm, but the short rains in some years are non-existent. The area is in the lower midland cotton
zone (LM3), with altitudes ranging from 1140 along the shores of Lake Victoria to 1450 inland. Average annual
0 0
mean temperatures are 22.7 -20.8 C. Two distinct soils are included in the study sites: low fertility orthic
ferrasols on hillside sweetpotato plots (sandy loams or kuoyo) and moderately fertile vertisols in swampy
locations (anywang’).
These four areas constitute an agro-ecological gradient of descending mean annual precipitation as one
moves inland from Rongo towards Kendu Bay, bordering Lake Victoria. In terms of yield potential for
sweetpotato, Kabondo ranks highest, Ndhiwa second, Rongo third, and Kendu Bay last. Note that in all areas
2
the peak planting period for sweetpotato occurs a month after the onset of the main rains, as priority is given to
planting maize and sorghum first.
Sampling Frame. A single visit, structured household survey was conducted among 81 key sweetpotato
growers, with 20 growers selected from each of four areas during a 2 week period in 1995 (1 week during May
and the second week in July). If more than one person was cultivating sweetpotato in the household, the grower
with the largest amount of land under sweetpotato production was interviewed. First, within a given area, lists of
sublocations having population densities of at least 150 persons per square kilometer, and known to produce
sweetpotato were constructed with assistance from the resident Ministry of Agriculture staff. One village was
randomly selected from sub-locations at least 7 kms from the main road, another among sub-locations within 2-3
kms of the main road. Ten households were subsequently chosen in both the near and distant village within the
sub-location using the following guidelines: 5 key growers under 36 years of age and 5 key growers greater than
35 years of age. Among those growers, at least four should be widows. Within these categories, farmers were
randomly selected from a list provided by the village elder. The final sample had 81 households, 21 in Rongo, 20
each in the remaining areas. The key sweetpotato growers interviewed comprised 43 growers over 35 years old,
38 growers under 36 years; 17 of the growers were widows, three of whom were less than 36 years old. This
framework was chosen so that agro-ecological, infrastructure and life-cycle effects could be adequately
examined. In addition, widows were selected as a representative sub-group for resource-limited households.
Results and Discussion
Importance of Sweetpotato As a Food Security and Cash Crop. Overall, sweetpotato’s most important role in
South Nyanza was as a supplementary food security crop, ranked 3rd in importance by 42% of farmers (Tab. 1).
Maize was the most important food security crop in all areas, except Kendu Bay, where sorghum ranked first in
90% of the households.
Only 59% of growers reported that a woman in the household was engaged in sweetpotato selling. Thirty-
two percent of the women ranked sweetpotato as their most important cash crop (Tab.1). Sweetpotato’s
importance as the principal cash crop varied considerably by area, with it being an extremely important source of
cash for women in Kabondo and to some extent Ndhiwa and Rongo (Tab. 2). Groundnuts was a far superior
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source of cash to sweetpotato for women in Rongo, and in Kendu Bay, groundnuts, cotton, and sorghum were
the most significant sources of cash.
Only 59% of the households had the principal man selling agricultural produce raised on the farm
independently of the woman. The most important cash crop for men differed in each agro-ecology: groundnuts
being most significant in Rongo, sweetpotatoes in Kabondo, sugar cane in Ndhiwa, and cotton in Kendu Bay
(Tab. 2). Not surprisingly, the average amount of cash obtained from sweetpotato sales during the year prior to
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the survey (the 1994/95 season) was highest in Kabondo (5766 Ksh) and lowest in Kendu Bay (500 Ksh) (Tab.
3). However, high standard deviations are seen for all mean values, indicative of the dichotomy between sellers
and non-sellers in each area.
At least 40% of growers in all areas increased the area planted to sweetpotatoes over the past 5 years
(Tab. 2). Ndhiwa had the highest number of growers increasing the amount of land planted to sweetpotato
(60%), whereas somewhat surprisingly, 26% of Kabondo growers were decreasing the amount planted to the
crop. Almost half of all growers felt yields of their sweetpotato were increasing, compared to 19% citing declining
yields, and 27% noting no major yield changes over the past 5 years. Declining sweetpotato yields appear to be
a particular problem in Kendu Bay.
Increasing sweetpotato consumption is occurring in a significant number of households in Rongo, Kabondo,
and Kendu Bay, while 70% of Ndhiwa farmers had levels of sweetpotato consumption similar to those 5 years
prior to the survey (Tab. 2). In contrast, the majority of farmers in all areas noted the positive trend of the
importance of sweetpotato as a cash crop. Sixty-two percent of the sample stated that their sales of sweetpotato
had been increasing during the last five years.
The decline in sweetpotato sales reported by 28% of Kabondo growers is disturbing, given the established
reputation of the area as a commercialized sweetpotato center. There are problems of market glut periodically
occurring in the Kabondo region, as an increasing number of farmers are selling their sweetpotatoes and many
tend to plant to target well-known selling periods, such as Ramadan. In addition, there may be increasing
competition from other parts of western Kenya where sweetpotato production for sale is also increasing.
Moreover, the tarmac road which has long served as the link to major markets in larger urban centers has
deteriorated significantly, with several farmers noting a consequent decline in larger trucks willing to transport
sweetpotatoes out of the area.
2
The Kenyan Shilling (Ksh) to U.S. dollar exchange rate fluctuated considerably during the 1994/95 period. An
average exchange rate of 45 Ksh/$1 U.S. can be used for comparative purposes.
4
Seasonality of Sweetpotato Consumption, Sales, and Purchases. The seasonal nature of sweetpotato
consumption, sales, and purchases is evident in Figure 2. Peak periods of consumption center around the
months of March through June (prior to the main maize harvest) in the well-rain fed areas, compared to August
through October in drier Kendu Bay. There are clear gaps in the calendar, particularly November through March
in Ndhiwa and Rongo, where sweetpotato could play more of an important role in the diet if made available as
other food sources (particularly maize) are low in stock in many households. Farmers in the well-rain fed areas
clearly rely on home grown sweetpotatoes for consumption. No Rongo farmer in the survey, for instance, ever
purchased sweetpotato. Only Kendu Bay farmers purchase sweetpotatoes in large numbers at certain times of
the year (e.g. March through July).
Selling of sweetpotatoes in Rongo occurs year-round on a small-scale basis. Very few Kendu Bay
households are actively engaged in selling sweetpotatoes, and roots planted during the main rains are all
harvested and disposed of by the end of October. In-ground storage is less of an option in Kendu Bay due to the
massive weevil infestation which occurs if roots are left in the ground beyond September.
While over a quarter of Kabondo farmers are selling sweetpotatoes in all months, except July through
October, Ndhiwa farmers concentrate their sales during the months of April through November. Periods of high
sweetpotato prices in Kabondo and Ndhiwa are juxtaposed next to those of the lowest prices. Before maize is
harvested in June and July, sweetpotato prices rise. As more sweetpotatoes mature from the middle and short
rain planting periods, a glut of fresh roots appear on the market, coincident with the start of the maize harvest,
and sweetpotato prices drop significantly.
Sweetpotato is predominantly sold fresh and consumed after boiling. Storage of fresh roots occurs in-
ground, with the roots being highly perishable once removed. Techniques of curing and longer-term fresh
storage are not known. However, 58% of farmers have prepared sweetpotato flour at some time in their life,
although only 52% of those that know how to prepare flour do so regularly. Sweetpotato roots are typically dried
by these households only when there is an excess production of sweetpotato roots.
Constraints. Farmers rated the severity of the problems the face in sweetpotato production, the results of which
are shown by area in Figure 3. Earlier work (Mutuura et. al., 1992 and Smit and Matengo, 1995) indicated that
moles are the greatest hazard to sweetpotato production in wet, higher elevations zones, while sweetpotato
weevils and lack of planting material are the predominant problems in drier areas. These results are confirmed
here, with one significant caveat. Sweetpotato weevil attack in roots was a severe problem for 30% and a
moderate problem for 55% of farmers in the well-rainfed area of Kabondo. This may indicate that intensification
5
of sweetpotato production in this area has enhanced the spread of weevil among closely spaced sweetpotato
plots. Since weevil infested roots are rejected by buyers, education of
farmers on preventive cultural practices should be given high priority for this area. Apparently, Ndhiwa farmers
suffer from significant mole infestations during the wet periods, while weevil attack is a major problem when their
black cotton soils crack in the dry season.
Over 40% of farmers in all areas reported insufficient family labor to assist in sweetpotato production.
Female labor is dominant in all sweetpotato activities except for field clearing whether or not sweetpotatoes are
strictly for home consumption. The contribution of male labor only becomes significant when sales of the crop
are important sources of household cash. While hired labor is readily available, its high cost was a also a major
constraint, particularly in Rongo. Kendu Bay residents had the fewest problems with lack of buyers and
transport, but this is no doubt due to the low level of sweetpotato commercialization in that area. Lack of
transport was the most severe problem from the marketing standpoint in Ndhiwa, Rongo, and even Kabondo.
Over a third of farmers complained of having problems finding a sufficient number of buyers as well. Clearly,
expansion of sweetpotato production on a large-scale is dependent on the development of support infrastructure
and the existence of sufficient market demand in relevant urban markets.
Determinants of Commercialization. Sweetpotato farmers are categorized on the basis of agro-ecology, distance
from their home to the main road, the amount of sweetpotato production sold and the level of sweetpotato sales
in 1994/95 in Table 4. Clearly, Kendu Bay farmers rely on sweetpotato for home consumption. Only farmers
near to the main road sold at least half of their sweetpotato production in Rongo. In contrast, a significant
proportion of farmers distant from the main road were able to overcome transport constraints in Kabondo and
Ndhiwa and sell half or more of the sweetpotato they produced.
Another way to examine the extent of commercialization is to categorize farmers on the basis of the total
amount of cash earned from sweetpotato during the previous year. Twenty-seven percent of growers earned
1000 Ksh or more in 1994/95, while 36% sold less than 1000 Ksh worth of sweetpotato, and 47% sold none
whatsoever. While farmers near to the main road in Rongo and Kabondo had higher average sale levels than
more distant farmers in those areas, the opposite held in Ndhiwa, where 50% of the more distant farmers earned
1000 Ksh or more, compared to 30% of farmers nearer to the main road. The randomly selected distant village
in Ndhiwa was found to have many farmers utilizing sweetpotato to feed pigs, a phenomenon not seen in any of
the other areas surveyed. Hence, there was a significant local market for sweetpotato roots in that location.
6
Ideally, one would like to have the actual percentage of total sweetpotato production sold as the variable
indicating the degree of commercialization. However, such precision for a piecemeal harvested crop such as
sweetpotato is difficult to achieve. Hence, two indicators were selected for use as limited dependent variables
for a probit analysis examining the determinants of sweetpotato commercialization. The first is a binary variable
for selling at least half of total amount of sweetpotato produced either in the short rains of 1994 or in the main
rains of 1995 (23 cases). The second is a binary variable representing the sale of at least 1000 Ksh worth of
sweetpotatoes during the same period (1994/95).
Independent variables consisted of variables reflecting agro-ecological zones (dummies for the study sites),
ease of marketing ( dummy for being within 2 kilometers of the main road), characteristics of the key
sweetpotato grower (sex, age, education), labor availability in the household (additional adult men and women
residing in the household besides the key sweetpotato grower), wage rates in alternative activities in which the
farmer was engaged, wealth (remittances from outside the household, per capita landholding size, agricultural
capital (tools plus livestock) and consumption (housing plus durable goods) indices, and resource control
(percent of land managed by the key sweetpotato grower and whether the head of household is polygamous).
Results for the probit analysis (using the software LIMDEP) are shown in Table 5. The predictive power of
the first model with the amount of sweetpotato sold as the dependent variable was greater than the second
model where the levels of sweetpotato sales is the dependent variable. The percentage of outcomes being
correctly predicted in first model was 78%, compared to 59% in the second.
Strongly significant positive determinants of commercialization in the first model were being within 2
kilometers of the main road, the availability of other adult women in the household, and regularly receiving
remittances from outside the household. The negative sign on the remittance dummy implies recipients
unearned income were less likely to sell significant amounts of their sweetpotato production. Moreover, the
majority of the remittance receiving households were in Kendu Bay. Male outmigration from Kendu Bay to seek
employment elsewhere is common and the best housing conditions were found in Kendu Bay in spite of the poor
agro-ecological setting. Thus, the negative coefficient in part results from Kendu Bay farmers not being involved
in commercial sweetpotato production. Interactions terms between the wealth indicators and the agro-ecological
dummies were included in the original model specification, but failed to be significant and were dropped.
Both of the education variables, the dummy for having finished primary school and that for having some
primary education, had negative signs and that for finishing primary school was weakly significant. The
7
implication is that more educated farmers were less likely to sell sweetpotatoes in significant quantities than their
counterparts with little or no formal education.
In the model with level of sales of sweetpotatoes as the dependent variable, only the availability of adult
men in the household was a strong positive determinant. In this model, the availability of additional adult women
was weakly but still positively significant. In addition, proximity to the main road, the key grower being male, and
land per capita were positive and weakly significant. Receiving remittances was also weakly significant, but with
the same negative sign.
Characteristics Preferred By Commercial versus Non-commercial Growers.
A list of desirable characteristics for a hypothetical sweetpotato variety was obtained from a subsample of
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41 farmers to discern if differences exist in preferences based on whether or not the farmer sells sweetpotato.
For several traits, all farmers are in agreement: the texture of the root must be dry, the vines should spread
horizontally as opposed to having an erect stance, and any new variety must be acceptable to buyers. The
majority also preferred little latex in the roots, although a few larger sellers noted latex is associated with
starchiness by many consumers, for whom abundant latex is a desirable trait. Several women also reported that
the gumminess associated with the latex makes the roots more difficult to slice and dry. There was also little
difference between sellers and non-sellers regarding the length of time storage roots should be able to stay in
the ground without rotting once mature. Overall, 49% desired storability for 3 to 4 additional months, 10% for 5
months, 20% for 6, with the remainder requiring longer periods of 8 to 12 months.
Some differences do exist, however, between characteristics desired by sellers and non-sellers. White-
fleshed varieties are highly preferred by sellers, whereas home consumers were equally divided between white
and yellow-fleshed sweetpotatoes. Sellers also desired red-skin color, while non-sellers liked both red and
purplish-red skinned varieties. Only 17% of farmers preferred white-skinned sweetpotatoes. All home
consumers wanted varieties which matured in 4 months or less, with 80% stipulating 3 months. In contrast,
while 80% of sellers wanted varieties maturing in 4 months or less, the remainder favored maturity periods
ranging from 5 to 9 months. Home consumers endorsed very sugary roots, whereas the top category of sellers
was equally divided between somewhat sugary and very sugary. Only 7% of the growers fancied roots that
were not sugary at all. The majority of home consumers want very large tubers (as one woman said, the larger
3
Due to the length of the questionnaire, only half the farmers in the survey were queried on this topic. Of these,
9 were farmers having sweetpotato sales in 1994/95 of 1000 Ksh and above, 17 with sales below 1000 Ksh, and
15 not selling whatsoever. Sellers in this section refer to those having any sales of sweetpotato whatsoever.
8
the better to impress your husband) compared to sellers who prefer medium size tubers (e.g. 300 gms) for ease
of packing into bags.
The desire for a variety that is weevil resistant was slightly more important to sellers than non-sellers, but
the main variation in preferences was by agro-ecology. Weevil resistance was critically important for the majority
of farmers in Rongo, Ndhiwa, and Kendu Bay, but not for those in Kabondo. Significant differences existed
between older and younger growers for this factor. Thirty-six percent of key growers under 36 years of age
thought weevil resistance was not an important criterion, compared to 15% of growers over 35 years of age.
Vine survival during the dry season was critically important characteristic for almost all farmers in Rongo,
Ndhiwa, and Kendu Bay. In contrast, 36% of Kabondo farmers felt the ability of vines to survive the dry season
was not important in a new variety. This probably reflects the ease with which planting material can be obtained
from others in the Kabondo area.
When queried as to what desirable characteristics the varieties they now possess lack, three main major
areas of concerned emerged: weevil resistance (44% of respondents), vine survival during the dry season
(39%), and storability of the roots in ground once they have matured (27%). It is somewhat surprising that early
maturity was not mentioned by Ndhiwa farmers, given the seasonal gaps in sweetpotato consumption previously
noted.
Conclusion
This paper has described preliminary results from a structured household survey on sweetpotato
commercialization in South Nyanza. Agro-ecological factors, distance to major roads, and adult labor availability
within the household were found to be key determinants of sweetpotato commercialization. The binary variable
of having sold at least one half of the total amount of sweetpotato produced either during the short or long rains
during the year prior to the survey emerged as a good indicator for assessing the degree of sweetpotato
commercialization. Farmers are particularly interested in new varieties which are weevil resistant, whose vines
can survive the dry season and whose roots can remain in the ground for at least an additional 3-4 months once
they have matured.
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REFERENCES
Jaetzold, R. and Schmidt, H. 1982. Farm Management Handbook of Kenya. Vol. II. Natural Conditions and
Farm Management Information. Part A. West Kenya (Nairobi: Ministry of Agriculture and GTZ), 397 pages.
Kenya Ministry of Agriculture. 1992. Annual Report 1991 (Nairobi: Ministry of Agriculture), 115 pages.
Mutuura, J.N., Ewell, P.T., Abubaker, A., Muga, T., Ajanga, S., Irungu, J., Omari, F. and Maobe, S. 1992.
“Sweet Potatoes in the Food Systems of Kenya: Results of a Socioeconomic Survey”. In J.N. Kabira and P.T.
Ewell (eds.), Current Research for the Improvement of Potatoes and Sweetpotatoes in Kenya. Proceedings of a
KARI/CIP Technical Workshop on Collaborative Research, Nairobi, November 1991 (Nairobi: CIP), pp. 51-66.
Smit, N.E.J.M. and L.O. Matengo. 1995. “Farmers’ Cultural Practices and their Effects on Pest Control in
Sweetpotato in South Nyanza, Kenya”, International Journal of Pest Management 41(1): 2-7.
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Table 1. Ranking of Importance of Sweetpotato as a Food Security and as a Source of Cash
(Percent of 81 Respondents)
Ranking: 1 2 3 4 5 6 NOT
Highest IMPORTANT
Food Security 0 5 42 21 14 6 12
Woman’s Cash Crop 32 15 7 1 3 1 41
Man’s Cash Crop 9 3 4 1 1 2 80
Table 2. Important Cash Crops and Trends in Sweetpotato Production and Consumption
Percent of Respondents within Site
Site: RONGO KABONDO NDHIWA KENDU ALL SITES
(Sample Size) (21) (20) (20) BAY (20) (20)
Most Important Cash Sweetpotatoe
Crop for Women: Groundnuts Sweetpotatoes s Groundnuts Groundnuts
Maize 15 4
Sorghum 15 4
Sweetpotatoes 24 70 30 5 32
Cassava 10 3
Groundnuts 71 5 25 25 32
Sugar Cane 5 5 5 4
Vegetables 5 5 5 4
Cotton 20 5
Fruit (Bananas, Oranges) 10 5 4
Legumes (e.g. Cowpeas) 5 5 5 4
Coffee 5 1
Most Important Cash
Crop for Men: Groundnuts Sweetpotatoes Sugar Cane Cotton
Maize 5 5 1 4
Sorghum 10 3
Sweetpotatoes 5 25 5 9
Cassava 5 1
Groundnuts 33 10 5 12
Sugar Cane 19 10 15 5 12
Vegetables 5 15 5
Cotton 20 5
Fruit (Lemons) 5 1
Legumes (e.g. Beans) 10 2
Coffee 10 2
During Past 5 Years:
Land Planted to SP:
Increasing 43 47 60 40 48
Decreasing 19 26 15 15 19
Same Amount 33 11 25 45 29
Yields of SP: Increasing 52 29 50 40 44
Decreasing 14 12 10 40 19
Same Amount 24 35 40 10 27
Home Consumption of
SP: Increasing 48 37 15 45 36
Decreasing 14 5 15 15 12
Same Amount 33 58 70 40 50
Sales of SP: Increasing 61 56 65 67 62
Decreasing 11 28 0 8 12
Same Amount 28 0 35 25 22
Table 3. Amount of Cash Obtained From Sweetpotato Sales in the Past Year: 1994/95
SITES: (Sample Sizes) RONGO KABONDO NDHIWA KENDU BAY ALL SITES
(14) (19) (16) (2) (51)
Mean Cash (Ksh) Obtained 702 5766 2038 500 3000
From SP : 1994/95 (Std. Dev.) (652) (8953) (2309) (565) (5703)
2
3
Table 4. Characteristics of Sweetpotato Production and Sales by Agro-ecology and Distance to Main Road
A. Percent of Respondents in Each Category
Site and Distance to Main Road: RONGO- RONGO- KABONDO KABONDO NDHIWA- NDHIWA- KENDU KENDU ALL
(Sample Size) Near FAR Near Far Near FAR BAY- Near BAY-Far SITES
(11) (10) (10) (10) (10) (10) (10) (10) (81)
Agro-Ecological Classification: LM1 LM2 UM2
LM1 LM2 UM1 UM3 LM3 LM2 LM3 LM3
Amount of SP Production Sold
in MAIN RAINS 1995:
Did Not Plant 18 30 30 30 40 18
None Sold 9 30 40 80 40 20 70 50 42
One-Quarter or Less 27 40 20 50 20 10 21
Half 36 10 6
More than Half 9 40 20 30 12
Amount of SP Production Sold
in SHORT RAINS 1994:
Did Not Plant 9 60 10 10 20 30 17
None Sold 9 20 10 30 20 70 70 28
One-Quarter or Less 36 10 30 30 10 12
Half 18 20 5
More than Half 27 70 40 10 20 21
Growers Earning:
1-999 Ksh on SP in 1994/95 64 40 20 60 40 40 10 10 36
1000 Ksh or More on SP in
1994/95 27 0 80 30 30 50 0 0 27
B. Averages (Standard Deviations in Parentheses)
Mean Household Size: 6.2 4.6 8.2 6.1 5.5 7.6 6.5 6.1 6.3
(1.3) (2.8) (2.0) (3.2) (1.6) (3.0) (2.0) (2.7) (2.4)
Average Education (Years): 5.4 1.9 6.4 4.7 3.7 3.4 6.0 1.9 4.2
Key SP Grower (4.0) (2.7) (2.3) (3.3) (4.2) (3.3) (3.8) (2.6) (3.3)
Mean No. SP Plots: 1.5 1.3 1.8 1.3 1.5 1.2 0.9 1.0 1.3
Key SP Grower (0.7) (0.7) (0.8) (0.4) (0.8) (0.4) (0.6) (0) (0.6)
Mean Size of Largest SP 0.11 0.09 2.71 0.43 0.08 0.13 0.08 0.22 0.48
Plot (Acres): Key SP Grower (0.11) (0.08) (4.34) (0.61) (0.05) (0.05) (0.14) (0.57) (1.71)
Mean No. Other Plots: 3.5 3.8 4.2 4.0 4.5 3.1 3.9 2.9 3.7
Key SP Grower (1.7) (0.6) (1.9) (2.4) (2.9) (1.4) (2.0) (1.5) (1.5)
Mean Agricultural Index: 21059 19957 56291 5494 26228 118875 41909 29146 39637
(Tools + Livestock) (18839) (29099) (50398) (4685) (28303) (169568) (43160) (20416) (71646)
Mean Consumption Index: 17514 13530 49478 11910 9464 35022 62913 13145 26509
(Housing + Goods) (23360) (21986) (54848) (9464) (11681) (55707) (58421) (7603) (40087)
Table 5. Probit Analysis For Selling at Least Half of Total Sweetpotato (SP) Produced
(HALF OR MORE SOLD) or Selling at Least 1000 Kenyan Shillings (Nominal) Worth of Sweetpotatoes During the
1994/95 Agricultural Season (1000 Ksh OR MORE), 4 Sites in South Nyanza, Kenya
(1000 Ksh Approximately Equals $22 U.S.)
HALF OR MORE SOLD 1000 KSH OR MORE SAMPLE
SOLD
Variable Coefficient Asymptotic Coefficient Asymptotic Mean Standard
t-ratio t-ratio Deviation
Constant -10.289 -0.252 -3.288 -0.075
Rongo Division 4.817 0.119 3.198 0.073 0.26 0.44
Kabondo Division 5.921 0.146 4.707 0.107 0.25 0.43
Ndhiwa Division 5.262 0.129 4.518 0.103 0.25 0.43
Within 2 Kms of tarmac road 1.172 2.020 0.860 1.583 0.51 0.50
Sex of Key SP Grower 0.235 0.161 1.440 1.418 0.09 0.28
(0=Female, 1=Male)
Age of Key SP Grower (Years) 0.036 1.281 -0.005 -0.218 40.85 14.35
Some Primary School -0.632 -0.814 -0.075 -0.104 0.49 0.50
(Key SP Grower)
Finished Primary School -2.299 -1.551 -1.327 -1.106 0.20 0.40
(Key SP Grower)
Other Adult Men (>13 Years) -0.001 -0.005 0.476 2.193 1.70 1.22
in Household
Other Adult Women 0.731 2.010 0.258 1.093 1.07 1.11
(>13 Years) in Household
Number Children under 6 0.422 1.420 0.122 0.530 0.91 1.05
Years in Household
Daily Wage Rate in Non-Farm 0.00003 0.013 0.001 0.289 53.59 88.69
Activity (Ksh/day)
Receives Regular -1.871 -2.322 -1.042 -1.424 0.30 0.46
Remittances from Outside
Per Capita Land Holdings 0.069 0.490 0.210 1.435 1.63 2.17
(Estimated Acres)
Percent of Land Managed by 0.008 0.707 -0.004 -0.500 51.01 32.91
Key SP Grower
Agricultural Capital Index 0.308 1.215 -0.212 -1.117 9.59 1.58
(Natural Logarithm)
Consumption Capital Index -0.095 -0.365 -0.632 -0.262 9.33 1.34
(Natural Logarithm)
Head of Household is -0.730 -1.158 -0.383 -0.690 0.23 0.42
Polygamous
Sample Size 81 81
Maximum Likelihood Estimates:
Log-Likelihood -23.52 -27.09
Restricted (Slopes=0) Log-L -48.33 -43.37
Chi Squared (18) 49.61 40.56
Significance Level 0.00008 0.002
Frequencies of Actual and Predicted Predicted
Predicted Outcomes: 0 1 TOTAL 0 1 TOTAL
Actual Actual
0 54 4 58 0 53 6 59
1 5 18 23 1 9 13 22
TOTAL 59 22 TOTAL 62 19
4
Figure 1. Mean Monthly Precipitation in Millimeters Near Research Sites and
Percent of Farmers Planting Sweetpotato
RONGO KABONDO
300 NDHIWA KENDU BAY
250
200
Millimeters
150
100
50
----------MAIN RAINS---------------------------- --MIDDLE RAINS --- ---SHORT RAINS----
0
MAY
JUL
JUN
MAR
NOV
FEB
DEC
AUG
OCT
SEP
JAN
APR
ANNUAL
RAINFALL
Months of the JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Year
1600 RONGO: 57 101 148 236 206 123 82 113 128 126 165 115
Monthly Rainfall
Percent Planting
1598 KABONDO: 39 69 292 179 218 141 136 184 127 92 65 55
Monthly Rainfall
Percent Planting
1372 NDHIWA: 55 87 122 245 195 89 35 59 93 125 148 119
Monthly Rainfall
Percent Planting
1134 KENDU BAY: 43 68 112 192 181 81 58 88 94 71 62 84
Monthly Rainfall
Percent Planting
LEGEND: NONE 1-19% 20-39% 40-69% 70% &
Sample Size=55 Above
Sources: For Kabondo, averages from three stations in Kabondo Division for 1994 (Oriang, Othoro, and Opanga), supplied by the local Ministry of Agriculture.
No meteorological stations were operating in the remaining areas. For Rongo, Ndhiwa, and Kendu Bay, averages for at least 10 years up to 1976, as provided
R. Jaetzold and H. Schmidt (1982), Farm Management Handbook, Vol. II, Part A, West Kenya, Russdorf, West Germany, p. 129.
Figure 2. Seasonal Distribution of Sweetpotato Consumption, Sales, Purchases and Prices
(Percent of Respondents Responding That Sweetpotato (SP) Activity Occurs in Given Month)
Sample Sizes: 13 for Rongo and Kendu Bay; 15 for Kabondo; 14 Ndhiwa; 55 Total
Months of the Year JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
SELL SWEETPOTATO: Rongo
Kabondo
Ndhiwa
Kendu Bay
HIGHEST SP PRICES: Rongo
Kabondo
Ndhiwa
Kendu Bay
LOWEST SP PRICES: Rongo
Kabondo
Ndhiwa
Kendu Bay
PURCHASE SWEETPOTATO:
Rongo
Kabondo
Ndhiwa
Kendu Bay
RELY HEAVILY IN DIET: Rongo
Kabondo
Ndhiwa
Kendu Bay
LOW OR ABSENT IN DIET: Rongo
Kabondo
Ndhiwa
Kendu Bay
LEGEND: None 1-19% 20- 40- 70% &
Percent responding that activity 39% 69% above
occurs in specified months
6
7
Percent of Sweetpotato Farmers In Each Division
100
0
10
20
30
40
50
60
70
80
90
Rongo
Kabondo
Ndhiwa
Kendu Bay
MOLES
Rongo
Kabondo
Ndhiwa
BIGGER
Kendu Bay
ANIMALS
Rongo
Kabondo
Ndhiwa
Kendu Bay
WEEVILS
Rongo
Kabondo
Ndhiwa
Kendu Bay
LACK OF
PLANTING
MATERIAL
Rongo
Kabondo
Ndhiwa
Kendu Bay
DROUGHT
Rongo
Kabondo
Ndhiwa
Kendu Bay
Rongo
THEFT
Kabondo
LOW
Ndhiwa
YIELDS
Kendu Bay
Rongo
Kabondo
Ndhiwa
LABOR
Kendu Bay
FAMILY
Moderate
LACK OF
Rongo
NOT
Kabondo
HIRED
LABOR
Ndhiwa
Kendu Bay
AVAILABLE
Severe
Rongo
Figure 3. Problems Reported By Farmers in South Nyanza
Kabondo
Sample Sizes: 21 in Rongo (R), 20 in Kabondo (K), Ndhiwa (N) and Kendu Bay (B)
HIRED
Ndhiwa
LABOR
Kendu Bay
COST OF
Rongo
Kabondo
Ndhiwa
BUYERS
LACK OF
Kendu Bay
Very Severe
Rongo
LACK OF
Kabondo
Ndhiwa
TRANSPORT
Kendu Bay
8
9